Aflatoxin Suppression by Modified Atmospheres Containing Carbon Monoxide

Aflatoxin production by Aspergillus flavus growing on potato-dextrose agar, cooked rice medium, and raw pistachio nuts, was suppressed in 2 ways. First, CO suppressed growth of the fungus if O 2 was low. Second, CO suppressed aflatoxin production, evidently by interfering with aflatoxin metabolism, even if the atmosphere permitted nearly normal fungal growth. Fungal growth was equal or better in 2% O 2 than in air (20.8% O 2 ). Addition of 10% CO slowed growth materially only if O 2 was low, but aflatoxin accumulation was suppressed by CO only slightly more in low O 2 atmospheres. After growth for 32 days at 20°C in cooked rice medium or raw pistachios in an atmosphere containing 2% O 2 + 10% CO, aflatoxin was <2% of the production in an atmosphere containing 2% O 2 or air without CO.